Motor speed actuated vehicle bumper

ABSTRACT

A motor actuated shock absorbing bumper has an improvement upon a variable rate spring used to absorb the energy of a collision, the improvement comprising a rate control for the spring, and means operated as a function of the speed of the vehicle for controlling the setting of the rate control such that the higher the speed at which a collision occurs, the stiffer the spring becomes. In its preferred form, the rate control comprises a piston, and the speed control comprises a variable pressure pump driven from the vehicle transmission output shaft and supplying liquid to the piston at a pressure which increases with the speed of the output shaft.

[ Feb. 5, 1974 1 MOTOR SPEED ACTUATED VEHICLE BUMPER [76 Inventor: JamesHrebicek, 2327 S. 61st Ave.,

Cicero, 111. 60650 [22] Filed: Jan. 6, 1971 [21] Appl. No.: 104,441

[52] US. Cl 180/91, 180/108, 267/116,

267/139, 26'7/172, 293/2, 293/9, 293/84, 293/87 [51] Int. Cl..... B60r19/06, B611 19/04, Fl6f 13/00 [58] Field of Search 293/2, 4, 9, 10, 68,70, 71,

393/86, 87, 84; 180/1 R, 1 AP, s2,91, 1

11/1967 Brock 293/9 ll/1961 Slemmons et a1 267/35 X PrimaryExaminer-Gerald M. Forlenza Assistant ExaminerHoward Beltran ABSTRACT Amotor actuated shock absorbing bumper has an improvement upon a variablerate spring used to absorb the energy of a collision, the improvementcomprising a rate control for the spring, and means operated as afunction of the speed of the vehicle for controlling the setting of therate control such that the higher the speed at which a collision occurs,the stiffer the spring becomes. In its preferred form, the rate controlcomprises a piston, and the speed control comprises a variable pressurepump driven from the vehicle transmission output shaft and supplyingliquid to the piston at a pressure which increases with the speed of theoutput shaft.

1 Claim, 3 Drawing Figures PAIENTEDFEB 51914 5.189.948

I N V E N TO I? James Hrcbz'cek MOTOR SPEED ACTUATED VEHICLE BUMPER Thisinvention relates to variable rate springs and to a control therefor.

In my U.S. Pat. No. Re. 25,697 there is disclosed a variable rate springused as a vehicle spring suspension. The rate of the spring isdetermined by the location of an abutment for the spring on the vehicleframe, the location of the abutment in turn being determined by amanually controlled fluid pressure system.

Recently, the high cost of collision damage sustained by automotivevehicles has made desirable the installation of energy absorbing deviceson or in connection with the bumpers of such vehicles. Such devices,however, do not take into consideration the fact that for a collision athigh speed the stiffness of the device should be greater than for one atlow speed. The manually controlled variable rate spring of my aforesaidpatent provides a device which is capable of adjustment by the operatorto increase its resistance with speed. However, just prior to acollision, the operator is generally occupied with manipulating thesteering wheel and may be holding the steering wheel with both hands tobrace himself against the shock of an anticipated collision. He, thus,is not able to adjust the manually controlled fluid pressure system toattempt to match the stiffness of the spring with the speed of theimpact.

The principal object of this invention is to provide a spring device forabsorbing the shock of a vehicle collision or the like, wherein theinitial resistance of the device is automatically adjusted in accordancewith the speed with which the device is actuated, such that the saidinitial resistance will increase to produce a stiffer spring as thevehicle speed increases.

Another object of this invention is the provision of a spring device foruse in the bumper system of a moving vehicle wherein the initialpressure of the spring is continuously varied in accordance with thespeed of the vehicle.

Yet another object of this invention is to provide a control system fora spring comprising a variable pressure fluid pump'driven by the outputshaft of an automotive vehicle change speed transmission, the output ofthe pump being used to vary the initial compression of a spring formingpart of a vehicle bumper system to increase the minimum force requiredto deflect the bumper system as the speed of the vehicle increases.

These and other objects of this invention will become apparent from thefollowing detailed description thereof when taken together with theaccompanying drawings in which:

FIG. 1 is a diagrammatic side elevational view of a vehicle in dottedoutline in which the present invention is installed;

FIG. 2 is an enlarged fragmentary side elevational view of the variablerate spring of this invention; and

FIG. 3 is an enlarged diagrammatic view of a variable pressure pumpsuitable for use in this invention.

Briefly described, this invention comprises a bumper operated spring,the initial compression of which is determined by the position of anabutment against which the spring bears. The abutment is connected to apiston which is subject to the output pressure of a variable pressurepump driven from the output shaft of the vehicle change speedtransmission. Pump pressure is made to increase as the speed of theoutput shaft increases, i.e., as the vehiclespeed increases.

Referring now to the drawings for a detailed description of theinvention, there is shown in dotted outline, a vehicle 10, which forpurposes of illustration may be taken to be a passenger automobile. Itis understood, however, that this invention can be used with any vehiclewhich is or can be equipped with a bumper, includ ing any of the highwayand railroad vehicles as well as off-the-road vehicles such as farmequipment and earth moving equipment. Said vehicle 10 is provided with afront bumper 11 which extends across the front of the vehicle 10 and isconnected by a thrust bar 12 to the active element 13 of a resilientshock-absorbing device which for purposes of illustration may be of thetype disclosed in my US. Pat. Nos. 2,877,011; 3,207,496 or Re. 25,697.Such prior devices are designed to produce a compression in one or moresprings 14, 15 by means hereinafter to be described, the initialcompression of said springs being determined by the position ofabutments controlled by hydraulic pistons 16, 17. The reaction of thethrust impressed upon the springs 14, 15 is taken by an abutment l8fixed to the chassis of the vehicle.

It is understood that vehicle 10 is provided with an engine-drivenchange speed transmission 19 the output shaft 20 of which is connectedto drive the rear wheels 21 of the vehicle and hence changes its speedas the vehicle speed changes. Said transmission output shaft 20 drives apump 22 (FIG. 3), preferably of the positive displacement type such as agear pump, the pump intake 23 being connected to the transmission oilreservoir 24 and the pump output 25 being connected to cylinders 26, 27in which pistons 16 and 17 operate. An orifice 28 of predetermined sizein the output 25 of pump 22 provides a means by which pressure of theoil in the output 25 increases with the speed of the output shaft 20.Other known means for producing an output pressure which varies with thespeed at which pump 22 is driven may be used in place of orifice 28.

The spring selected to illustrate this invention is shown in greaterdetail in FIG. 2. Active member 13 is connected to abutment 18 by one ormore telescoping guides 29, 30. Secured to active member 13 and abutment18 are cams 31 and 32 which have substantially identical cam surfaces 33and 34 on which ride triangular follower carriages 35 and 36 pivotallyconnected together at their apices 37. Said apices are also pivotallyconnected to a recessed spring holder 38 in which one end of spring 14is retained. The other end of spring 14 is received in a spring holder39 connected by a piston rod 40 to piston 16.

Cylinder 26 is connected by links 41 and 42 to cams 31 and 32 or to somepart rigidly connected to active element 13 and abutment l8. Said levers41 and 42 cause cylinder 26 to move in the same direction as the apices37 of carriages 35, 36, but at a different rate, the rate beingdetermined by the lengths of said levers and by the disposition of theirconnections to active element 13 and abutment 18. The shapes of thesurfaces 33, 34 on cams 31, 32 determine the rate at which the apices 37move. The difference in the rates of movement of cylinder 26 and apices37 determines the rate at which spring 14 is compressed.

It is understood that spring 15 is operated by a system of cams,carriages and levers in the same manner as spring 14, the illustrationand description thereof being omitted herein for brevity.

Cam surfaces 33 and 34 are each formed with a depression 45 and 46 intowhich one of the rollers 47 and 48 of each of the carriages fall whenthe spring is extended to its maximum length. Said depressions restrainthe rollers and carriages from moving until a predetermined force isapplied against active element 13,

i.e., against bumper 11. This avoids deflections of spring 14 underminor, harmless impacts or collisions, and allows the metal of thebumper to take directly so much of the shock as the operator of thevehicle can safely stand before calling the spring into play.

In operation, the piston 16 will assume a position in its cylinder 26dictated by the pressure of the fluid in said cylinder. This pressurewill be proportioned to the speed of the vehicle so that at highervehicle speeds the pressure will be higher, thus preloading spring 14 tocause it to require a greater force to compress it per unit .ofdeflection. Since the force of a collision increases as a function of avehicle speed, the increased spring pressure will prevent a prematurecollapse of the spring at higher vehicle speeds.

Telescoping guide part 30 may be made to retard the movement of part 29thereinto in accordance with the speed of the vehicle. Thus part 30 maybe formed with a recess 49 in which is disposed a spool-shaped bushing50 made of Nylon or the like, said bushing being retained in recess 49by a threaded cap 51. The space 52 around the spool is connected to pumpoutput 25 so that it is subjected to the same pressure as piston 16. Theconstruction of bushing 50 is such that the higher the pressure in space52 the tighter will be the fit between bushing 50 and guide part 29passing therethrough. This increased tightness increases the brakingeffect of bushing 50 upon part 29 and hence contributes to the increasedstiffness of the shock absorbing device as a whole as the speed of thevehicle increases.

Although the device of FIG. 2 shows piston 16 connected directly tospring holder 39, said piston may take a form (not shown) in which it isconnected to said spring holder by an intervening rack and pinionturning a nut which advances or retracts a screw connected to saidholder 39.

The specific disposition of the shock absorbing device of this inventionon a vehicle is a matter of design to be determined by the appearance ofthe vehicle and the location of its frame, spring, shock absorbing andsteering members. Similar shock absorbing devices can be located betweenthe rear bumper and vehicle frame, or at any point on a vehiclerequiring protection against shock loads. Where the vehicle does nothave a change speed transmission, such as a railroad car, the fluidpressure pump can be driven by some member rotating with the vehiclewheels.

I claim:

1. In combination a spring, an abutment for the spring, an activeelement adapted to engage the spring to expand or contract said springagainst said abutment, a variable speed shaft, means intermediate theabutment and spring and movable as a function of the speed of said shaftfor changing the position of said abutment relative to said spring, andtelescoping guide means connecting the active element and the abutment,and means for retarding the movement of said telescoping guide means asa function of the speed of said shaft.

1. In combination a spring, an abutment for the spring, an activeelement adapted to engage the spring to expand or contract said springagainst said abutment, a variable speed shaft, means intermediate theabutment and spring and movable as a function of the speed of said shaftfor changing the position of said abutment relative to said spring, andtelescoping guide means connecting the active element and the abutment,and means for retarding the movement of said telescoping guide means asa function of the speed of said shaft.